Pollution Assessment of Industrial Effluents Discharged into the Aba River, Abia State, South East Nigeria

The Aba River in Abia State receives effluent discharges from numerous small and medium-scale industrial operations including textile dyeing, plastic manufacturing, and food processing plants located in the Aba industrial corridor. This study assessed the physicochemical and heavy metal composition of industrial effluents discharged into the Aba River and their impact on river water quality. Effluent samples were collected directly from five industrial discharge points, and river water samples were taken upstream and at four downstream stations. Parameters measured included pH, temperature, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total suspended solids, and concentrations of lead, chromium, cadmium, and zinc. Results showed effluent pH values ranging from 4.1 to 10.8, indicating both strongly acidic and alkaline discharges. Biochemical oxygen demand and chemical oxygen demand in effluents exceeded NESREA permissible limits at all five discharge points. River dissolved oxygen levels declined progressively downstream of industrial zones, falling below 3 milligrams per litre at the most distal station. Chromium and lead concentrations in downstream river water exceeded national drinking water standards. The study recommends mandatory installation of effluent pre-treatment systems by industrial operators, routine NESREA inspection of industrial premises, and development of a clean production incentive programme for the Aba industrial zone. Keywords: industrial effluent, Aba River, heavy metals, NESREA, water pollution.